1. Technical Field of the Invention
The present invention relates to the field of antennas, and more particularly to an electronic card assembly having a retractable antenna.
2. Description of the Prior Art
Electronic card assemblies containing devices such as modems and pagers for use with portable terminals are gaining increasing importance in the telecommunications area. These card assemblies are used with portable terminals such as portable computers, laptop computers and personal digital assistants (PDAs) to allow data transfer and communication between the portable terminal and a wireless network. A common form for these card assemblies is a plug-in modular unit that may be plugged into a slot on a host terminal and, furthermore, easily unplugged and removed for transportation or easily changed to allow communication with different wireless networks. The increasing importance of these electronic card assemblies is of such a magnitude that it has caused a movement toward standardization in the computer and telecommunications industry. For example, the Personal Computer Memory Card International Association (PCMCIA) has set forth a widely used standard that defines a 68 pin interface and slot and assembly dimensions for the interface between a card assembly and a host terminal. Card assemblies that conform to this standard are known as PCMCIA cards.
When a card assembly such as a PCMCIA card is used for data transfer and communication between a host terminal and a wireless network it is necessary that some sort of antenna be provided. Ideally, any antenna provided should be optimized for communications using the frequencies of the particular wireless system in which the host terminal is operating. Additionally, an antenna external to the host terminal and not permanently built into the terminal device would be advantageous. This would prevent the need for designing an antenna for use in one wireless system into the portable device without certainty as to the actual wireless systems the device would be operating in, when the antenna may not be optimal for use in other systems. An antenna external to the host device would also prevent the need for a connection between the electronic card assembly and host terminal separate from the PCMCIA interface, such as a coaxial cable and connectors to connect the card assembly receivers and/or transmitters to the antenna in the portable terminal. This type of connection would be bulky and expensive for use in a portable system.
An antenna contained in the card assembly would offer the above mentioned advantages of an antenna external to the host terminal. An antenna of this type could be configured to receive or transmit specifically on the frequencies of the wireless system the card assembly is designed to communicate with. The antenna and card assembly could be contained in a single package, which could be easily inserted into and removed from the host terminal, allowing ease of setup for wireless communications and easy transportation. The single package would prevent the need for coaxial cable and connectors to connect the card assembly to the antenna, further facilitating portability.
The location of an antenna contained within an electronic card assembly is a critical factor in attaining optimum RF reception at the antenna and, optimum performance of receiver and/or transmitter circuitry contained within the assembly. For example, present day electronic card assemblies containing receiving and/or transmitting devices utilize miniaturized components and, consequently, when a card assembly is inserted into a standard recessed PCMCIA slot a significant number of the components and circuits of the assembly may be enclosed within the walls of the host terminal surrounding the slot. When the card assembly is so enclosed, significant RF interference between the host terminal and the receiver and/or transmitter of the electronic card assembly can occur. To prevent this interference electronic shielding is often placed within the card assembly, or in the host terminal itself, around the area of the terminal surrounding the recessed PCMCIA slot. If the card assembly or area of the host terminal surrounding the PCMCIA slot is shielded, the placement of an antenna within the PCMCIA card assembly results in a receiver and/or transmitter enclosed by shielding and with degraded performance. Because it is desirable to shield the card assembly or area of the host terminal surrounding the PCMCIA slot, it would be advantageous to locate the antenna as far as possible from the enclosed portion of the card assembly. Additionally, it is always advantageous to have the antenna far enough away from the host terminal to minimize RF interference between the antenna and electronic components in the host terminal.
Locating an antenna contained within a card assembly away from the enclosed portion of the card assembly and away from the host terminal may result in a card assembly package of awkward shape or size. For example, PCMCIA card assemblies are manufactured to dimensions that form a single compact package. An external antenna on a PCMCIA card assembly may prevent placement of the card assembly in a pocket or case for easy transportation. Also, an exposed external antenna may be subject to breakage during transportation.
It would provide an advantage then to have a portable electronic card assembly having an antenna optimized for use with receiver and/or transmitter circuitry in the electronic card assembly, where the performance of the antenna is not degraded by being located in close proximity to a host terminal, and where the dimensions of the electronic card assembly are not increased by the antenna when the antenna is not in use. Additionally, it would be advantageous if the antenna did not affect portability by requiring bulky and expensive connectors. It is a shortcoming and deficiency of the prior art that such an electronic card assembly has not yet been made.